1. Field of the Invention
This invention relates to polyesteramines with good dye affinity for anionic dyestuffs and to the process for their production.
More particularly, it relates to polyesteramines containing tertiary amino groups sited in the polymer chain or laterally in relation to the chain, and made from diols containing at least three carbon atoms in the molecule.
It relates also to yarns and fibers made from these polymers, as well as to molded articles.
2. Description of the Prior Art
Polyesters derived from aromatic dicarboxylic acids, particularly from terephtalic acid and aliphatic, saturated alicyclic or cycloaliphatic diols containing at least three carbon atoms in the molecule are of great commercial interest due to a variety of end uses as a result of their high tenacity, flexibility, crease resistance, etc.
The yarns and fibers made from these polymers, however, are not easy to dye since there are no reactive sites in the macromolecular chains. Although there exist many techniques to add dye holding components to fibers, they all fail to improve the dye affinity for polyesteramines.
In U.S. Pat. No. 2,739,958 spinnable aromatic polyesters containing tertiary amino groups in the molecule, at the level of at most 1% by weight of nitrogen in relation to the polymer, are prepared by mens of either bis-(.omega. -hydroxyalkyl)-alkylamine where the alkyl chain joining hydroxyl groups is preferably as short as possible, bis(.omega.-hydroxyalkyl)-arylamine or aralkylamine, or bis(.omega.-carboxyalkyl)-alkylamine, -arylamine or aralkylamine compounds.
These compounds carry on the nitrogen atom at least an alkyl group having only one or two carbon atoms. These compounds cannot improve the dyeability of polyesters made from diols having at least three carbon atoms in the molecule.
In U.S. Pat. No. 2,744,086 a mixture of acrylic polymers and homopolyesters which are made from carboxylic diacids, glycols containing one or several tertiary amino or quaternary ammonium groups in the chain are used where the tertiary amino groups can be made from diacids corresponding to the formula: ##STR1## or from diols corresponding to the formula: ##STR2## with x, y = 1 or 2
z = 0 or 1 PA1 R = alkyl, aralkyl or a cycloalkyl group.
The homopolyesters alone do not produce a yarn exhibiting good textile quality. The diols, on the other hand, only improve to a slight degree the dye affinity of polyesters made from diols containing at least three carbon atoms in the molecule for anionic dyestuffs. Besides, as indicated in this patent, they are designed for obtaining homopolyesters only and are only used in mixtures with acrylic polymers.
In U.S. Pat. No. 2,647,104, polyethylene-glycol terephthalate is modified by treating the polymer at 100.degree.-275.degree.C with functional aminated compounds until the polymer is made dyeable with acid or direct dyestuffs, but this treatment must be stopped before yellowing. In order to be dyeable, polymers should contain from 0.15 to 0.4% nitrogen. Such a process, however, requires a technically complicated and critical treatment. Furthermore the nitrogen ratios necessary for good dye affinity are high which reduces the profitability of the process from a commercial standpoint.
It is also known to improve polyolefin dyeability by the addition of a polyester resin containing tertiary amino groups at the level of 0.1 to 2% by weight of nitrogen in relation to the whole composition. These polyester resins, however, can only be used in mixtures and are not spinnable alone.
Finally, in German application 2,150,293 polyesters are modified with tribenzylamine or its derivatives. But the dyeability obtained with this type of compound is very little.
It has now been found that polyesteramines with a good dye affinity for anionic dyestuffs can issue from:
a. at least an aromatic dicarboxylic acid and possibly a small quantity of an aliphatic diacid,
b. at least an aliphatic, saturated alicyclic or cycloaliphatic diol having at least three carbon atoms in the molecule, and
c. at least a compound corresponding to the formula NR.sub.3 in which R being identical or different represents alkyl, saturated alicyclic cycloalkyl or arylaliphatic groups, one, two or three of the R groups carrying zero, one, two or three ester generating groups with the total number of the ester generating groups being from 1 to 3. Two of the R groups can form a cycle between them, but at most only 2 R groups can be saturated alicyclic or arylaliphatic or cycloaliphatic radicals containing one carbon atom only between the cycle and the nitrogen atom. The NR.sub.3 compound must have at least 3 carbon atoms between the ester generating groups and the nitrogen, and the proportion of the NR.sub.3 compound or compounds used is such that the percentage of nitrogen fixed on the polymer is at least 0.03% by weight in relation to the polymer.
This invention relates also to all shaped articles obtained from these polymers, such as filament yarns, staple fibers, woven and knitted fabrics, molded articles, etc.
It relates also to a process for the production of said polyesteramines, in which the diol having at least three carbon atoms is allowed to react with the methyl ester of the diacid and the compounds corresponding to the formula NR.sub.3 are added when at least 90% by weight of the theoretically produced methanol is eliminated from the reaction medium.
In a preferred embodiment the aminated compound or compounds are introduced about 10 minutes before attaining the pressure and temperature conditions which bring about the vaporization of the compounds in order to avoid their immediate vaporization.
It is particularly surprising to see that on adding the compound or compounds corresponding to the formula NR.sub.3 at the beginning of the reaction, i.e. before 90% of the theoretically produced methanol is eliminated from the reaction medium, the compound or compounds decompose to a great extent whereas, later on, when 90% of the theoretical methanol is produced, said compound or compounds are nearly entirely recovered in the final polymer. The temperature at which the beginning of the reaction is carried out is in any case lower than the temperature at which this compound or compounds are introduced in the reaction medium. This criterion applies to whatever polymer type is desired or whichever aminated compound or compounds are introduced. This embodiment is especially advantageous when using less stable aminated compounds.
Among all the diols presently known for the production of polyesters made from aromatic diacids and particularly from terephthalic acid, it has been found that only diols containing at least three carbon atoms are suitable for the production of polyesteramines according to the invention. On polyesteramines made from diols containing less than three carbon atoms, such as ethyleneglycol and containing the same compounds with tertiary amino groups, there is observed only a little improvement of the dye affinity and an unsatisfactory yellowing.
In the same way, by polycondensating compounds containing tertiary amino groups of the prior art with a diol containing at least three carbon atoms and at least an aromatic diacid, polyesteramines with good dyeability are also not obtained.
Surprisingly, it has been found that a double selection was necessary:
a. the use of diols having at least three carbon atoms in the molecule, and
b. the use of compounds with particular tertiary amino groups.
By compounds with tertiary amino groups are meant those compounds corresponding to the general formula NR.sub.3, in which R is identical or different and represents either alkyl, saturated alicyclic, cycloalkyl or arylaliphatic groups with one, two or three R groups carrying zero, one, two or three ester generating groups. The total number of ester generating groups is from 1 to 3 with the possibility that two of the R groups form a cycle, but no more than two of them being arylaliphatic or cycloaliphatic radicals comprising one carbon atom only between the cycle and the nitrogen atom, or saturarted alicyclic radicals.
In addition, the number of carbon atoms between the ester generating group or groups and the nitrogen atom is at least 3 and preferably comprises between 3 and 20.
The ester generating groups may be --OH, --COOR', or anhydride groups with R' being a hydrogen atom or an alkyl group. The compound may contain different ester generating groups, and particularly, it may contain COOR' and OH groups simultaneously.
Compounds with tertiary amino groups may also be polycondensated with any suitable compound such as an aliphatic or aromatic diacid, for example, before being added to the reaction mixture.
The tertiary amino groups of said compounds may not be situated on the polymer chain, but in a lateral configuration in the case where two ester generating groups are placed on the same R group.
Among usable compounds, N,-N-.omega.-dihydroxyalkylamines, such as the N,N-.omega.-dihydroxyhexyl-hexylamine or the N,N-.omega.-dihydroxyhexyl-benzylamine, or N,N-(di-.omega.-alkylalcanoates)alkylamines such as the N,N(dimethylhexanoate) hexylamine, the N(methyl-5methylisophthalate)piperidine.
If desired, a small amount of an aliphatic diacid and/or a polyethyleneglycol may be added, for example up to 10% by weight in relation to the total weight of the polymer.
The compounds with tertiary amino groups are used in such quantities that the percentage of nitrogen on the polyesteramine obtained is higher than 0.03% by weight in relation to the weight of the polymer.
The percentage of nitrogen fixed on polymer may be from 0.05% to 0.5% by weight, though the superior limit may be higher, but prefereably from 0.05 to 0.13%. However, the use of percentages higher than 1% is of little interest with regard to dye affinity and it does not save much. As a result of using the process according to the present invention the loss of aminated compounds is very low.
The polymers obtained exhibit a good dye affinity for anionic dyestuffs and this is particularly attractive when these polymers are designed for spinning. These polymers may also be molded in the conventional manner.
The color of the articles obtained, after dyeing with anionic dyestuffs, exhibits good light-fastness, washing-fastness, dry cleaning-fastness and sublimation-fastness.
When preparing yarns for use in textiles, it is possible to dye wool and polyesteramine blends simultaneously. Such a technique is of great practical interest and is very economical.
In the following examples, dyestuffs are mentioned by their reference CI (Colour Index, edition 1971 and its additions) and the viscosity index VI is determined from the viscosity in solution measured at 25.degree.C on a solution of 1% by weight per volume of polymer in orthochlorophenol by the formula: ##EQU1## in which the concentration is expressed g/100 cm.sup.3. The parts and percentages are given on a weight basis.